1. Field of the Invention
The disclosures herein relate to a touchpad and a method of making the same.
2. Description of the Related Art
Electronic devices having a fingerprint authentication function have been used more and more. The position at which a device for fingerprint authentication is disposed varies from electronic device to electronic device. For example, some touchscreen panels have a substrate, a touch sensing structure disposed on the substrate, and a fingerprint authentication module mounted on the substrate, such that the touch sensing structure and the fingerprint authentication module are disposed on the same side of the substrate (see Patent Document 1, for example). Such touchscreen panels are structured such that the fingerprint authentication module is mounted to the substrate via an adhesive layer.
As in the touchscreen panel disclosed in Patent Document 1, a device for fingerprint authentication (i.e., the fingerprint authentication module in the case of Patent Document 1) may be made to adhere to a member (i.e., the substrate in the case of Patent Document 1) having an operating surface on which an input operation is performed, thereby helping to simplify the entire structure, with expectations for improvements in design freedom and productivity.
From the viewpoint of enhancing the position detection function of a touchscreen panel, the thickness of a member (which will hereinafter be referred to as a “operating plate”) having an operating surface on which an inputting operation is performed may be decreased. Such a decrease made in the structure described above may increase the risk of having a problem as follows.
A decrease in the thickness of an operating plate makes the operating plate more likely to be warped when pressed by a finger for the purpose of fingerprint authentication. This warpage serves as a peel force which causes the fingerprint authentication device glued to the operating plate to break off partially, resulting in a failure to detect a fingerprint. In this manner, decreasing the thickness of an operating plate in a touchscreen panel with added features such as a fingerprint authentication device may cause the added features to fail to function properly due to the warpage of the operating plate during use.
It may be desired to provide a touchpad having a structure in which an added feature part attached to the operating plate is unlikely to break off even when the thickness of the operating plate is decreased, and may also be desired to provide a method of making such a touchpad.